Fuel, such as gasoline, diesel fuel and the like, is severely impaired if water or particulate matter is admixed with it. Most fuel, such as gasoline, diesel fuel and so forth, as used in internal combustion engines is seriously effected by the presence of water. First, of course, water is not combustible and therefore subtracts from the energy value available from a given quantity of fluid. Second, water freezes easily and can block fuel lines in cold environments. Third, water tends to carry with it contaminates and more readily reacts with metals to form rust. For these and other reasons, it is very important that in order to preserve high fuel quality, water must be prevented from traveling in a fuel flow system.
One method to intercept water in a fuel system is to provide a fuel filter media of the type that permits fuel, such as gasoline, diesel fuel or the like, to pass therethrough, but which resists the passage of water. Filters of this type include hydrophilic material that absorbs and expands in the presence of water, but which are not olephilic, that is, that do not absorb hydrocarbons.
In a fuel flow filtering system it is highly desirable that positive shut off be provided so that when sufficient water is detected in a fuel flow system, such as by water absorptive fuel media swelling or otherwise reacting to resist the further fuel flow therethrough, a positive mechanical type shut off is obtained. U.S. Pat. No. 4,485,011 to Cole et al discloses a type of shut-off valve in conjunction with a fuel filter arrangement. Reference may also be had to U.S. Pat. No. 4,959,141 to Anderson which discloses an improvement in the Cole et al device. In the Cole et al and Anderson devices, a ball is maintained in position when the pressure drop across a filter media is below a certain level but is displaced when the pressure drop increases, such as occurs when the filter absorbs water. The ball is then passed to a valve closure position to stop further fuel flow through the filter. The concepts of the Cole et al U.S. Pat. No. 4,485,011 and Anderson U.S. Pat. No. 4,959,141 are good and useful and are significant advancements of the state of the art. However, some problems exist with the critical manufacturing tolerances employed in both the Cole et al and Anderson devices. The devices disclosed in each of these patents include one or more washer-type elements that are deformed by a ball as pressure differential across the ball increases. It can be easily understood that the thickness of the washer, the diameter of the opening through the washer, the diameter of the ball, the deflection of the washer in the manufacture process, and so forth, are exceedingly critical to permit the ball to pass through the washer or washers at the proper elevated pressure differential, but which do not permit the ball to pass through at lower pressure differentials. While the concepts of the Cole et al and Anderson patents are good, manufacturing products to fulfill the objectives of these patents has proven to be somewhat difficult.
The present disclosure is an improvement in the basic concepts disclosed in the Cole et al and Anderson patents. Particularly, the present disclosure is intended to accomplish essentially the same objective of these two previously issued patents, that is, to close off fuel flow through a filter when the amount of water and contaminants absorbed by the filter has caused a differential pressure to build across the filter to a preselected level and to thereafter stop all further fuel flow through the filter.
The present disclosure accomplishes essentially the same objectives of the Cole et al and Anderson patents without using a ball and washer arrangement, and in a way that permits more carefully controllable manufacturing tolerances to thereby provide for a fuel filter having a method of fuel cut off that is easier to manufacture and a filter having a more predictable level of differential pressure that actuates the filter to close off against further fuel flow.